This application claims priority benefits under 35 USC xc2xa7119 of Japanese Patent Application Serial No. 2001-269133, the disclosure of which is incorporated by reference.
1. Field of the Invention
The present invention relates to a steering locking device for preventing an automobile from being stolen.
2. Description of Related Arts
The above-mentioned steering locking device has an annular collar fitted in an outer periphery of a steering shaft so as to be relatively rotatable through an annular spacer and a locking device main body fixed to a steering column, for example.
The locking device main body is provided with a locking pin which can advance and retreat. The locking pin advances into the steering column at the time of steering locking and is engaged with a hole in the collar, thereby preventing the collar from being rotated. Correspondingly, the steering shaft is prevented from being rotated.
When a torque applied between the steering shaft and the collar exceeds a defined torque value, the annular spacer allows the collar to be rotated relative to the steering shaft. When an excessive torque is applied to the steering shaft in a steering locked state, therefore, the steering shaft can be rotated, thereby preventing the locking device from being damaged.
The above-mentioned annular spacer forms a wave shape, the tops of the wave shape being arranged along its circumference. The annular spacer is pressed between the steering shaft and the collar along the axis of the steering shaft.
In order to precisely manage the defined torque value, strict dimensional accuracy is required with respect to the respective components such as the annular spacer, the steering shaft, and the collar. Therefore, the processing cost of each of the components rises. As a result, the manufacturing cost of the steering locking device rises. Further, the annular spacer forming a wave shape is complicated in structure and is high in cost. Accordingly, the manufacturing cost of the steering locking device further rises.
An object of the present invention is to provide a low cost steering locking device which allows a locked steering shaft to be rotated when a torque exceeding a defined torque value is applied to the steering shaft.
In a preferred mode of the present invention, a steering locking device for restraining the operation of a steering wheel at the time of locking comprises a collar surrounding a steering shaft which is rotated integrally with the steering wheel; an annular clearance formed between an outer periphery of the steering shaft and an inner periphery of the collar; a spacer press-fitted in the annular clearance and formable into a circular arc shape surrounding the steering shaft; a locking device main body fixed to a fixing member such as a jacket of a steering column; and a locking member supported on the locking device main body and displaceable to a locked position for preventing the collar from being rotated and a locking released position. The relative rotation between the steering shaft and the collar is restrained by the spacer in a case where a torque applied to the steering shaft is not more than a predetermined torque when the collar is prevented from being rotated by the locking member at the locked position. The spacer is formed of members which are woundable around the steering shaft from the outside of the collar through the opening of the collar.
According to the present embodiment, the spacer can be easily assembled in the annular clearance. The spacer is also autonomously adjusted to actual diameters of the steering shaft and the collar to be assembled. As a result, the respective dimensional tolerances of components such as the spacer, the steering shaft, and the collar may not be made strict, thereby making it possible to reduce the costs of the components.
Preferably, the spacer is connected to either the steering shaft or the collar so as to be integrally rotatable. When the spacer is connected to the steering shaft, for example, so as to be integrally rotatable, frictional resistance between the spacer and the steering shaft need not be considered. Consequently, surface roughness of an opposite portion between the spacer and the steering shaft may not be strictly managed. As a result, the costs of the components can be further reduced.
Moreover, a state where the spacer is press-fitted is suitably adjusted as the diameter is adjusted. Accordingly, the value of the predetermined torque hardly varies.